Numerous medical procedures require the insertion of an instrument, such as an endoscope, down a person's mouth and into the body. Such is the case when performing, for example, an Esophagogastroduodenoscopy (EGD), a procedure comprising the insertion of a flexible endoscope through the mouth until reaching the duodenum (first and shortest part of the small intestine). The endoscope when inserted is used to provide a visual inspection of the organs, and optionally to perform medical procedures such as, for example, biopsies, incisions, and retrieval of foreign objects.
Endoscopic procedures are usually performed while a patient is under topical or moderate sedation, although in some circumstances it may be performed while the patient is under general anesthesia. During moderate sedation or general anesthesia the patient is generally sedated intravenously to minimize gagging and to facilitate the procedure. A bite block is used to prevent the patient from biting on the endoscope, to facilitate the introduction of the endoscope into the mouth, and to maneuver the endoscope relatively freely while inserted in the mouth.
A frequent occurrence when administering intravenous sedation is reduced breathing in the patient, which may lead to hypoxia, or a reduction of oxygen in the blood. It is then substantially common practice to administer oxygen or another breathable gas to the patient, usually through a nasal cannula, while the patient is sedated. Additionally, the patient's exhaled breath is typically monitored, by means of a capnograph, in order to corroborate that the patient's carbon dioxide levels in the blood and the tissues are within safe limits.
A number of bite blocks have been adapted with features to supply oxygen, or optionally some other type of breathable gas, to a sedated patient. Some have been further adapted with features which allow the patient to be connected to a capnograph for measuring the carbon dioxide contents in the patient's exhaled breath. The following patents and/or publications describe different types of bite blocks adapted with some of these features, all of which are incorporated herein by reference.
U.S. Pat. No. 5,273,032 “Oxygenating Oral Medical Appliance”, describes an “endoscopic mouth guard having a smoothly contoured, waisted tube merging into a peripheral flange at the front end of said tube, a manifold integral with the front face of said flange defining a closed ended, transverse distribution duct, and two open ended, upwardly directed branch ducts ending, in use, closely below the nostrils of a patient fitted with the guard, two further, open ended branch ducts extending rearwardly from said distributor duct into the bore of said tube, and a laterally and rearwardly directed tapered spigot on said manifold, defining an extension of said distributor duct, adapted to enter the bore of a gas supply tube. The finished guard is a single article of plastics material having a smooth hard surface.”
U.S. Pat. No. 5,513,634 “Combination Integral Bite Block Airway and Nasal Cannula”, describes a “combination plastic relatively rigid bite block and soft nasal cannula intended for one-time use for supplying oxygen to a patient's nostrils during an endoscopic procedure. The cannula is fixed into the bite block by an integral clip portion of the cannula extending downwardly from a manifold portion and adhered to the bite block. Flexible nasal prongs extend upwardly from the manifold into the patient's nostrils to supply supplementary gas separately from air breathed through the patient's mouth.”
US Patent Application Publication No. US 2007/0006878 A1 “Capnographic-oxygenating Oro-fiberscopic Bite block”, describes an oro-fiberscopic bite block. “The bite block is utilized during oral fiberscopic procedures. The bite block includes a main structure having an orifice sized to accommodate entry of a fiberscope, such as an endoscope, through the orifice. The bite block includes an extension extending inward from the main structure when positioned within the mouth of a patient. On each side of the orifice is a loop for handling and positioning the bite block within the patient's mouth. The bite block includes an exhalation tube running from the extension to a monitoring device which allows monitoring of the patient's expelled gases. In addition, an inhalation tube may be used to provide supplemental oxygen to the patient. The bite block is positioned in the mouth of the patient with the mouth of the patient surrounding the extension. The tubes include openings which are located on the extension and lie in the interior of the mouth to provide monitoring of uncontaminated gasses expelled by the patient.”
PCT International Application Publication No. WO 2007/063532 “Endoscopic Bite Block”, describes a “bite block assembly adapted for capnography and oxygen delivery to a subject, the bite block assembly including a first capnography passageway adapted for passage therethrough of exhaled breath from the subject to a capnograph and a second oxygen delivery passageway, separate from the first passageway, adapted for passage therethrough of oxygen from an oxygen source to the mouth of the subject.”
There is still a need in the art for improved bite blocks, systems including them and methods that would allow efficient breath sampling during medical procedures such as endoscopy.